Please tell me why my calculations are wrong. Thanks!
In the coordinate plane, line k passes through the origin and has slope 2. If points (3,y) and (x,4) are on line k, then x+y=
(A) 3.5
(B) 7
(C) 8
(D) 10
(E) 14
Answer: C
My calculations:
Since slope is 2 and k passes through the origin, the y-intercept is zero. Thus y=2x. Since we know that points (3,y) and (x,4) are on line k, then that means,
(4-y)/(x-3) =2.
10=2x+y
Given that y=2x, I set the two equations, 10=2x+y and y=2x, equal to each other and got x=2.5 and y=5. Clearly this isn't the right answer. Why are my calculations wrong?
Thanks for your help!
In the coordinate plane, line k passes through the origin and has slope 2. If points (3,y) and (x,4) are on line k, then x+y=
(A) 3.5
(B) 7
(C) 8
(D) 10
(E) 14
Answer: C
My calculations:
Since slope is 2 and k passes through the origin, the y-intercept is zero. Thus y=2x. Since we know that points (3,y) and (x,4) are on line k, then that means,
(4-y)/(x-3) =2.
10=2x+y
Given that y=2x, I set the two equations, 10=2x+y and y=2x, equal to each other and got x=2.5 and y=5. Clearly this isn't the right answer. Why are my calculations wrong?
Thanks for your help!
